Sorry Umair, but you’re dead wrong (also I am disappointed as I was expecting a bit better of you).
Bernie is a socialist. He isn’t a communist, sure, which is what’ you’re actually saying. Nationalisation is one of the two forms of enforced common ownership that characterises communism.
The central idea in communism is the rejection of private property and that’s done in 2 ways: nationalisation and collectivisation. First one is enforced ownership by the state and the second one is enforced ownership through “free” association between private individuals.
The central idea in socialism is the society in terms of state-mandated “I have your back” policies (eg: social security / public pensions / public healthcare / public transportation and so on). States in which social policies are central to policymaking and administration are generally called socialists (think France, the European nordic countries, Greece, etc).